Implement RFC 3631: add rustdoc doc_cfg features #138907

GuillaumeGomez · 2025-03-24T22:50:33Z

This implementation actually resulted in a lot of simplifications:

All cfg computation is now done in one place: propagate_doc_cfg.rs. Because (trait) impls are not retrieved at the same time as the other items, we cannot perform this computation in the clean process, it needs to be after.
Because there is cfg inheritance, we can keep track of them in one place (in propagate_doc_cfg.rs), meaning we don't need to copy an item's attributes to its children anymore. Only exception: impl items. For them we clone only cfg attributes.
propagate_doc_cfg.rs is also now much simpler, much less need to keep track of parents, since everything we need is handled by the new CfgInfo type.
I also suspect that Cfg::simplify_with could either be removed or at least used directly into propagate_doc_cfg.rs when we compute cfgs. Considering how big the PR already is, I'll do it in a follow-up.

I didn't remove the doc_cfg* features in this PR because some dependencies used in rustc (like stdarch) are using it, so we need to have a nightly released with this PR before I can switch to the new feature.

r? ghost

petrochenkov · 2025-03-25T09:48:06Z

What remains to be done:

I'd also want to block the stabilization on landing #138844 to avoid a stable rustdoc feature relying on externally observable hacks in rustc.
The crater run in #138844 returned mostly clean, so I expect it to land soon.

GuillaumeGomez · 2025-03-25T10:36:45Z

Noted! And that will be a nice improvement, thanks!

Just one thing left for the cfg expansion missing: #[cfg_attr(blabla, derive(Debug))]. In this case, the cfg is not kept in the generated derive items. It's been in my TODO list for a long time now. ^^'

petrochenkov · 2025-03-25T10:49:31Z

Just one thing left for the cfg expansion missing: #[cfg_attr(blabla, derive(Debug))]

Do you mean like in #138515? :)

GuillaumeGomez · 2025-03-25T10:52:03Z

You're my hero! Gonna need to handle this new attribute then. :)

bors · 2025-03-25T17:53:10Z

☔ The latest upstream changes (presumably #138923) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2025-03-27T19:41:02Z

☔ The latest upstream changes (presumably #138927) made this pull request unmergeable. Please resolve the merge conflicts.

It looks like the issue with building the latest docs originated from rust-lang/rust#138907 getting into effect at docs.rs.

`doc_auto_cfg` has been removed in the latest nightly, see rust-lang/rust#138907. This feature was merged into `doc_cfg`. This fixes the rustdoc build in the latest nightly toolchain with docsrs feature enabled.

doc_auto_cfg was merged into doc_cfg in rust-lang/rust#138907

Since rust-lang/rust#138907 was merged.

`doc_auto_cfg` has been removed in the latest nightly, see rust-lang/rust#138907. This feature was merged into `doc_cfg`. This fixes the rustdoc build in the latest nightly toolchain with docsrs feature enabled.

It looks like the issue with building the latest docs originated from rust-lang/rust#138907 getting into effect at docs.rs.

See rust-lang/rust#138907

Rust nightly removed this: ``` error[E0557]: feature has been removed --> internal/interpreter/lib.rs:4:38 | 4 | #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))] | ^^^^^^^^^^^^ feature has been removed | = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information = note: merged into `doc_cfg` ```

the `doc_auto_cfg` feature has been merged into `doc_cfg` [1], and this is breaking building vm-memory documentation on docs.rs [2]. [1]: rust-lang/rust#138907 [2]: https://docs.rs/crate/vm-memory/0.17.0/builds/2564760 Signed-off-by: Patrick Roy <[email protected]>

Rust nightly removed this: ``` error[E0557]: feature has been removed --> internal/interpreter/lib.rs:4:38 | 4 | #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))] | ^^^^^^^^^^^^ feature has been removed | = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information = note: merged into `doc_cfg` ```

reference: rust-lang/rust#138907 Signed-off-by: Tomasz Pietrek <[email protected]>

See rust-lang/rust#138907, also see [#linebender > Cargo doc failures in linebender repos](https://xi.zulipchat.com/#narrow/channel/419691-linebender/topic/Cargo.20doc.20failures.20in.20linebender.20repos/with/542106544).

`doc_auto_cfg` has been removed from the current Rust version, which caused rustdoc breakages. See rust-lang/rust#138907

doc_auto_cfg was merged into doc_cfg in rust-lang/rust#138907

- fix some links - replace doc_auto_cfg with doc_cfg as instructed by the failed docs.rs run [INFO] [stderr] 253 | #![cfg_attr(iroh_docsrs, feature(doc_auto_cfg))] [INFO] [stderr] | ^^^^^^^^^^^^ feature has been removed [INFO] [stderr] | [INFO] [stderr] = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information [INFO] [stderr] = note: merged into `doc_cfg`

## Description Try to fix docs.rs docs generation - fix some links - replace doc_auto_cfg with doc_cfg as instructed by the failed docs.rs run [INFO] [stderr] 253 | #![cfg_attr(iroh_docsrs, feature(doc_auto_cfg))] [INFO] [stderr] | ^^^^^^^^^^^^ feature has been removed [INFO] [stderr] | [INFO] [stderr] = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information [INFO] [stderr] = note: merged into `doc_cfg` ## Breaking Changes None ## Notes & open questions Not sure how to test this. ## Change checklist  - [ ] Self-review. - [ ] Documentation updates following the [style guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text), if relevant. - [ ] Tests if relevant. - [ ] All breaking changes documented. - [ ] List all breaking changes in the above "Breaking Changes" section. - [ ] Open an issue or PR on any number0 repos that are affected by this breaking change. Give guidance on how the updates should be handled or do the actual updates themselves. The major ones are: - [ ] [`quic-rpc`](https://github.com/n0-computer/quic-rpc) - [ ] [`iroh-gossip`](https://github.com/n0-computer/iroh-gossip) - [ ] [`iroh-blobs`](https://github.com/n0-computer/iroh-blobs) - [ ] [`dumbpipe`](https://github.com/n0-computer/dumbpipe) - [ ] [`sendme`](https://github.com/n0-computer/sendme)

See rust-lang/rust#138907